Power ladder and safety device for workman&#39;s basket



Aug. 13, 1968 E. v. GARNEYTT POWER LADDER AND SAFETY DEVICE FORWORKMAN'S BASKET Filed June 13, 1966 3 Sheets-Sheet 1 INVENTOR. F EDWARDV. GARNETT ATTORNEYS Aug. 13, 1968 E. v. GARNETT POWER LADDER AND SAFETYDEVICE FOR WORKMANS BASKET 5 Sheets-Sheet 2 Filed June 13, 1966 R E N RWA m6 V D R A W D E n? ATTORNEYS 1968' E. v. GARNETT 3,396,814

POWER LADDER AND SAFETY DEVICE FOR WORKMAN'S BASKET Filed June 13, 19665 Sheets-Sheet 3 30 Fig-6 I INVENTOR. EDWARD V. GARNETT BY V Mum- $MATTORNEYS United States Patent 3,396,814 POWER LADDER AND SAFETY DEVICEFOR WORKMANS BASKET Edward V. Garnett, 2300 E. 40th Ave., Denver, Colo.80205 Filed June 13, 166, Ser. No. 556,998 Claims. (Cl. 182-2) ABSTRACTOF THE DISCLOSURE A line means, such as a cable, having one endconuected to a workmans operating support and the opposite end movablewith a portion of an extending and retracting device for an outersection of a ladder which is extended and retracted with respect to aninner section, such portion of the extending and retracting device beingmovable in the opposite dirction. A motion opposing device, such as ashock absorber, prevents the workmens support from suddenly tipping, inthe event of breakage of the cable. Also, a hollow hand rail forms aguide for a portion of the cable which maintains the workmans support invertical position. Additional details of the extending and retractingdevice are also disclosed.

This invention relates to power ladders and also to safety devices forworkmens baskets, such safety devices being particularly useful inconnection with baskets mounted on a power ladder, but useful also inconnection with workmens baskets mounted on other types of apparatus onwhich a workmans basket may be mounted, such as derricks, aerial liftsand the like.

Among the objects of this invention are to provide a novel power ladder;to provide such a power ladder having an extensible and retractableouter section, on the outer end of which a workmans cage or basket ismounted; to provide such a power ladder in which the workmans basket ismaintained in an upright position, irrespective of the angularity of theladder or the position of the extensible and retractable section of theladder; to provide such a power ladder in which the means formaintaining the workmans basket in an upright position includes a cable;to provide a safety device for such a basket which will prevent thebasket from tipping suddenly and tending to throw the operator out, inthe event that the cable breaks or a similar mishap occurs; to providesuch a safety device which is adapted to be utilized with workmensbaskets or cages which are mounted on other types of apparatus,including derricks, aerial lifts and the like; to provide such a safetydevice which will operate effectively but will not materially impede themovement of the basket during normal operation of the ladder, aeriallift or the like; to provide such a ladder in which a workman in thebasket is adequately insulated against contact with a high voltage lineor the like; to provide such a ladder in which the ladder sections areso constructed that the leveling connection to the basket is accuratelyguided and is protected against damage, particularly when the ladder isin storage position; to provide such a ladder in which the means forextending and retracting an outer section of the ladder cooperates withthe basket leveling means; and to provide such a ladder and such asafety device which are relatively easy to construct and efiicient andeffective in operation.

Additional objects and the novel features of this invention will becomeapparent from the description which follows, taken in conjunction withthe accompanying drawings, in which:

FIG. 1 is a three quarter side perspective view of an aerial ladder ofthis invention, provided with a safety device of this invention andmounted upon a vehicle, showing the ladder in a raised and partiallyextended position;

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FIG. 2 is a side perspective view of the aerial ladder and vehicle ofFIG. 1, showing the ladder in a storage or transport position;

FIG. 3 is a fragmentary, longitudinal section, on an enlarged scale andtaken near the o posite edge of the ladder of FIG. 1, showing the insideof the basket and a portion of the outer ends of two sections of theladder;

FIG. 4 is a fragmentary, condensed side elevation, on a further enlargedscale, of a portion of a slightly modified form of the ladder of FIG. 1,in the retracted position of FIG. 2, showing the outer and inner ends ofthe ladder sections, with certain portions broken away to show partsotherwise hidden from view;

FIG. 5 is a fragmentary, top plan view of a portion of the structure atthe inner end of the ladder, showing particularly sheaves for a cablethrough which the basket is maintained upright and a drive sprocket forone of a pair of chains by which the outer section of the ladder isextended and retracted; and

FIG. 6 is a transverse section, on a further enlarged scale, taken alongline 66 of FIG. 4.

As illustrated in FIGS. 1 and 2, a ladder, to which the principles ofthis invention may be applied, includes an inner section I, which ispivotally mounted at its inner end on a rotatable turret T, and an outersection 0, which is extensible from and retractable within the innersection I and at the outer end of which is mounted a workmans basket B.The turret, in turn, may be mounted upon a vehicle V, such as a paneltype truck having a cab 10 and a pair of storage panels 11 extendingrearwardly from the cab on opposite sides of the truck bed. In order toreach an elevated point at which work is to be done, the workman standsin the basket B, either entering the basket originally or climbing upthe ladder to the basket after the basket has been positioned, as bypivoting the inner section I about a pair of pivot pins 12, connected toside plates 13 of the turret T or also to additional supporting andreinforcing members within the turret. The turret T is preferablyrotatable to any position around a full circle at any desired time,irrespective of the angular elevation of the inner section I.Simultaneously therewith, or later if desired, the inner section I maybe pivoted upwardly or downwardly and the outer section 0 may beextended from the inner section I until the basket B reaches the desiredposition. For storage purposes, the outer section 0 is fully retracted,with a portion of the basket fitting within the outer end of section I,and the turret T rotated until the inner section I is directly above asupporting stand S, then lowered onto the stand, as in FIG. 2. The standS may include a pair of spaced uprights 14- and an upper cross bar 15provided with upwardly extending stops 16, which prevent the ladder fromshifting laterally during transportation. Thus, the stops 16 are spacedapart a distance slightly greater than the total width of the innersection I between the outer surfaces of its side panels 17 and .18. Theelevation of cross bar 15 is preferably such that, with the ladder instorage position, it will extend over the cab 10 but will not interferewith the vision of the driver of the vehicle.

As described above, the ladder of this invention includes many of thefeatures of the ladder disclosed and claimed in my copending applicationSer. No. 547,531, filed May 3, 1966, thus including a hydraulic cylinder19 for pivoting the ladder upwardly and downwardly, the piston rod ofthe cylinder being connected to a closed box section 20 extendingbetween depending portions 21 of the sides 17 and 18 of the innersection I, as well as a central post 22, about which the turret T isrotatable and which is mounted upon the bed of the truck and maintainedin vertical position by angular braces 23, connected at their inner endsto post 22 and at their outer ends to cross bars 23, with boltsextending through the outer ends of the braces and cross bars throughthe bed and connected to the frame of the truck beneath the bed. Theturret T may be rotated about the post by a motor driven. pinion (notshown) engaging a ring gear 25, while the motor for driving the pinionmay be either an hydraulic motor or an electric motor, powered throughan hydraulic pump or an electric generator driven by a separate gasolineengine mounted within the turret T or from the engine of the vehicle V.In order to permit the operator to climb onto or off the ladder, theturret T is provided with a series of steps 26, as in FIGS. 1 and 2,with a hand rail 27 at the outside of each step. As will be evident, forshifting the ladder from the storage posi tion of FIG. 2 to a useposition, the ladder is merely elevated until, upon rotation, the ladderclears the tops of stops 16, after which the turret T may be rotated toany desired position. As will be evident, when operating at either sideor to the rear, the outer end of the ladder may be lowered until thebasket B rests on the ground. It will be evident, of course, that, inlieu of the hydraulic cylinder 19, angular movement of the ladder may beobtained by a motor driven screw or any other suitable type of drive.

As also disclosed in my aforesaid application Ser. No. 547,431, thesides 17 and 18 of the inner section I, as in FIG. 6, may be formed ofsteel and provided with an upper flange 28 which extends inwardly andthen downwardly, as well as an inwardly extending lower flange 29. Thesides 30 of the inner ladder section I may be formed of a fiberglassreinforced plastic, such as a polyester resin, formed integrally as abox section or from a pair of interfitting channels, as shown, securedtogether by a suitable adhesive, such as an epoxy resin. This hollowplastic beam section not only insulates the basket B from the flow ofelectric current, but also is resistant to damage by weather, as throughwater, while the interior of the box section may be filled with a light,expanded polyurethane foam, to prevent water from collecting inside. Aspaced series of tubular metal rungs 31 extend between the sides 17 and18 of inner section I and are attached thereto in a suitable manner, asby welding, while a series of hollow, tubular fiberglass reinforcedplastic rungs 32 extend between the insides of beams 30 of the outersection of the ladder, being attached thereto in a suitable manner, asby brackets 33 and bolts 34. A series of plates 35 extend upwardly fromthe inside edges of the hollow beams 30, at spaced longitudinalpositions, and each carries at its top a sleeve 36 through which extendsan insulating rod 37, formed of reinforced plastic and attached to theopposite ends of the corresponding hollow beam by a con nection 38, asin FIG. 1, at which tension on the rod 37 may be obtained to increasethe structural strength of the beam. Rod 37 also provides an insulatedhand rail for the outer section 0. Each of the sides 17 and 18 of theinner section I is provided with upwardly extending flanges 39, whichmay be formed integrally therewith, or welded thereto, and to the upperends of which a tubular hand rail 40 is welded.

The basket B, as in FIGS. 1 to 3, is pivotally mounted between the outerends of beams 30, as by a pin 41 extending inwardly from each beam, asin FIG. 3, and is provided with a controller C, mounted at the top ofthe basket for ready access by the user and provided with a controlhandle 42 which is conveniently adapted to be moved to differentpositions to cause the turret T to rotate to one side or the other, tocause the ladder to be pivoted upwardly or downwardly by cylinder 19, orto cause the outer ladder section to be extended or retracted. Controlcables 43 connect the controller with the various mechanisms by whichthe above movements are produced, while a similar controller is mountedon or within turret T, or on one of the vehicle panels 11, to enable theposition of the basket to be controlled from the vehicle or from theground. The cables 43 extend along the inside of one of hollow beams 30,or within the same, and into a conventional take-up reel (not shown)mounted on the inside of a side plate of ladder section I or within theturret T, to accommodate extension and retraction of the ladder section0. The basket B itself is formed of an insulating material, such as afiberglass reinforced polyester resin, and has a base 44, side walls 45,a front wall 46 and a rear wall 47. The front and side walls arepreferably provided with an offset 48 adjacent the base 44, toaccommodate the toes of the operator standing in the basket, while thefront wall 46 is provided with a bumper 49, to minimize the possibilityof damage to the basket through accidental contact with a line pole,cross bar, or the like. The upper ends of the side walls and front wall46 also conveniently flare outwardly, to facilitate the operator leaningout of the basket in performing his work. The rear wall is also providedwith a forward offset 50, conveniently just above the center of heightof the basket, and also an opening 51 which extends downwardly to apoint below offset 50, for readier access to the basket by the workmanfrom the ladder. The rear edges of the side walls 45 conform to thecontour of the rear wall 47, while the base 44 is spaced above the loweredges of the walls, as shown, to provide a depending rim which willsupport the basket when placed on the ground.

The outer section 0 of the ladder is moved inwardly and outwardly by apair of continuous chains 53, which pass around a pair of idlersprockets 54, mounted on a shaft 55 near the outer end of the laddersection I, and also around a pair of drive sprockets 56, as in FIGS. 4and 6, near the inner end of the ladder section I and mounted on a driveshaft 57, which is journaled, as in FIGS. 1 and 5, in a bearing 58 ateach end. Each chain 53 is attached to a lower corner of the side of theouter section 0, adjacent the inner end thereof, as by a bracket 59 ofFIG. 4. Also, a guide and support bar 60 is attached, as by welding, tothe tops of metal rungs 31, not only to guide the chains during movementof the ladder section 0 along ladder section I, but also to support theladder section 0. Thus, the guide bars 60 are narrow to fit within thechain and permit the chain rollers to roll along the guide bars, as willbe evident from FIG. 6, in which a space is shown between the undersideof beams 30 and chains 53, as well as between the rollers of chains 53and guide bars 60, for clarity of illustration, it being understood thatthe rollers of the upper reach of chains 53 will engage the guide bars60 and that beams 30 will rest directly on the chains. As will beevident, when the drive sprockets 56 are rotated to move the upper reachof the chain 53 outwardly, the outer ladder section 0 will be extended,while when the drive sprockets 56 are rotated in the opposite direction,the upper reach of the chains 53 will be moved inwardly and the outerladder section 0 will be retracted. Thus, through a suitable drivemotor, either electric or hydraulic, connected to drive shaft 57, butbeing conventional and therefore not shown, the outer ladder section 0may be moved to any desired extended or retracted position. For holdingladder section 0 laterally, a conventional guide shoe or roller (notshown) may be placed on the inside of each side plate 17 and 18, at theupper end thereof, as at the position of reinforcing plates 61, while asimilar conventional guide shoe (not shown) may be mounted at the lowerend of each beam 30, on the outside thereof, so that the upper guideshoes or rollers will engage the outside of the corresponding beam 30and the lower guide shoes or rollers will engage the inside of therespective plate 17 or 18.

In accordance with this invention, a basket leveling device, whichmaintains the basket in upright position, irrespective of rotation ofthe turret, inclination of the ladder or extension or retraction of theouter ladder section, is associated with the extension and retractionmeans and with a fixed point relative thereto, as on turret T.Preferably, such leveling device includes a cable 63, one

end of which is connected to the lower reach of chain 53, as through asocket 64 of FIG. 3, so that this end of the cable will move with thelower reach of the chain 53, i.e. when the upper reach of the chain 53is moved outwardly, the lower reach will be moved inwardly and tend toprovide slack in the cable 63, but when the upper reach of the cable 53is moved inwardly, to retract the ladder section 0, the lower reach ofthe chain will be moved outwardly, thus producing a pull on cable 63.

Cable 63 may be connected to basket B through an extension 65 attachedto basket B at a laterally extending pin 66 of FIGS. 1 and 2, butpreferably through an insulating rod 67, the end of which adjacentbasket B, as in the modified form of FIG. 4, is connected to a socket68, as by a suitable adhesive, in turn pivoted on a pin 69, which ismounted on a bracket 70, attached to the rear wall 47 of the basket,adjacent offset 50 and outside opening 51.

In further accordance with this invention, when either the cables orrods 67 are utilized, each will be received in the corresponding tubularhand rail 40, as in FIG. 6, which serves as a guide therefor, and willmove within the hand rail a distance sufiicient to maintain the basketin a level position. The insulating rod 67 may be connected at its innerend to a hollow socket 71, in one end of which the inner end of rod 67is received and connected, as by a suitable adhesive, and the oppositeend of which is threaded to receive an adjustment stud 72, integral withor attached to a socket 73, which provides a connection for that end ofcable 63. It will be understood, as indicated above, that when the cable65 of FIGS. l-3 is utilized, it will form merely a continuation of thecable 63 of FIG. 4.

As will be evident, the movement of the socket 64 and corresponding endof cable 63 will correspond directly to the extension or retraction ofthe outer ladder section 0, so that, without any change in angularposition, the basket will be maintained at the same angle with respectto the outer section 0. In order to accommodate a change in the angularposition of the ladder and still maintain the basket in an uprightposition, irrespective of the angular position of the ladder, the cable63 passes over a fixed sheave 75, mounted on a pin 76 extendinglaterally outwardly from a bracket 77 of the turret T, as well as anintermediate sheave 78 mounted on the inner ladder section I and a guidesheave 79 mounted on drive shaft 57, alongside sprocket 56. A pair ofpins 80, as in FIGS. 4 and 5, extend laterally outwardly from bracket77, to restrain any movement of cable 63 off fixed sheave 75. As will beevident, sheaves 75, 78 and 79 may be positioned so that, when theladder is moved angularly downwardly and the basket would otherwise tendto tip forwardly, the fixed sheave 75, particularly, produces a pull onthe cable, which maintains the basket in an upright position. Similarly,when the ladder is moved angularly upwardly, the basket will otherwisetend to tip rearwardly, but the fixed sheave 75, particularly, tends toproduce a slack in the cable which is taken up by the overhanging weightof the basket or the overhanging weight of the basket and the operatortherein, or by extension of the ladder section 0, when accompanying thesame, thereby again maintaining the basket in an upright position. Itwill be understood, of course, that the angular movements of the ladderare normally such that the cable 63 and rod 67, or cable 63 and itscontinuation 65, will relatively easily follow the movement of theladder.

In further accordance with this invention, a safety device is provided,so that, in the event either cable 63 or cable 65 or rod 67 breaks, orthe connection between the leveling cable and the chain 53 breaks, thebasket will not be tipped suddenly forwardly, tending to throw theoperator out of the basket. This is accomplished through the use of amotion opposing device D, which is mounted between a point near theouter end of the outer section O and the basket B, as in FIG. 3. Such adevice may comprise a shock absorber which includes a cylinder 82pivoted on a pin 83 extending inwardly from a bracket 84 attached to theinside of one beam 30 of the outer ladder section, and a rod 85 whichenters the cylinder 82 and is provided with a conventional air piston,as well as being pivoted on a pin 86 mounted on a bracket 87 attached tothe rear wall 47 of the basket, just below the olfset 50. A similarmotion opposing device D is preferably installed adjacent the oppositeside of the basket B but is merely a duplicate of that shown in- FIG. 3.As will be evident, through the motion opposing device D, any suddenmovement of the basket B is opposed, giving the operator time to climbout of the basket and onto the ladder, in the event that the levelingcable breaks or a similar mishap occurs. Since the pin 41, by which thebasket is pivotally connected to the outer end of the outer laddersection 0, is adjacent the rear wall of the basket, the weight of thebasket and also the operator therein is overhanging, thus producing atendency for the basket to tip over suddenly, in the event the levelingcable breaks, or a similar mishap occurs, However, through the use ofthe motion opposing device D, the initial tipping movement will be veryslow. Also, the motion opposing device D does not interfere with thenormal leveling of the basket. As indicated previously, the basketremains in the same angular relation to the outer section of the ladder,when the outer section is extended or retracted, and it is only when theangular pivotal position of the ladder is being changed that the angularrelationship between the basket and the outer section of the laddershould be changed in a corresponding amount. However, a motion opposingdevice, such as a shock absorber, will accommodate slight movements witha minimum of opposition, but will oppose longer or sharper movement witha much greater force. Thus, a conventional shock absorber is ideal foruse at the motion opposing device D.

From the foregoing, it will be evident that the requirements and objectshereinbefore set forth have been fulfilled to a marked degree. Through acable which is attached to the means for extending and retracting theouter section of the ladder, which cable passes over a fixed sheave onthe turret, the workmans basket may be maintained in an upright positionat all times, irrespective of extension or retraction or change in theangular position of the ladder. The hollow upper hand rail of the lowerladder section forms a convenient guide for the basket leveling cable.When an insulating rod is substituted for a portion of the basketleveling cable and the outer section of the ladder is also formedprimarily of insulating material, grounding of the basket is avoided, sothat, if the operator accidentally comes into contact with a highvoltage line, there is much less possibility of injury to the operator.Through the use of a motion opposing device between the outer end of theladder and the basket, any sudden changes in position of the basket areopposed, thus giving the operator sufiicient time to climb out of thebasket and onto the ladder, in the event the leveling cable breaks. Aswill be evident, such a levelin g device and also such a safety devicemay be installed in a similar manner on other types of apparatus inwhich a workmans basket is mounted, such as derricks, aerial lifts andthe like.

Although a preferred embodiment of this invention and certain variationsthereof have been illustrated and described, it will be understood thatother embodiments may exist and various other changes may be made therein, all without departing from the spirit and scope of this invention.

What is claimed is:

1. Apparatus for positioning a workmans operating support in anelevatedposition, including boom means adapted to be mounted onrotatable supporting means, in turn adapted to be mounted on a vehicle,and comprising:

an inner section pivotally mounted at its inner end on said supportingmeans;

means for pivoting said inner section upwardly and downwardly;

an outer section mounted on said inner section for extension andretraction with respecet thereof;

means for extending and retracting said outer section support as definedin claim 1, including:

a motion opposing device connected between said support and the outerend of said outer section.

3. Apparatus as defined in claim, 2 wherein:

said motion opposing device comprises a shock absorber.

4. A power ladder comprising apparatus for positioning a workmansoperating support as defined in claim 1, wherein:

said inner section is an inner ladder section having sides and rungsextending transversely between said sides; said outer section is anouter ladder section having sides and rungs extending transverselybetween said sides; said means for extending and retracting said outersection with respect to said inner section includes line means having aportion movable in the same direction as said outer section and anotherportion movable in the opposite direction; and said workmans operatingsupport is pivotally mounted on the outer end of said outer section. 5.In a power ladder as defined in claim 4, wherein: said sides of saidouter ladder section and the portion of said position maintaining linemeans adjacent said support are each formed of insulating material. 6.In a power ladder as defined in claim 4, wherein: at least one side ofsaid inner ladder section is provided with a hollow hand rail forming aguide for a corresponding portion of said position maintaining linemeans. 7. A power ladder, as defined in claim 4, wherein: said positionmaintaining line means includes a cable extending around a sheavemounted on said supporting means. 8. A power ladder as defined in claim4, wherein: said extending and retracting line means includes a pair ofendless roller chains connected to the inner end of the underside of therespective sides of said outer ladder section and rotatable sprocketsfor said chains mounted adjacent the outer and inner ends of said innerladder section;

a drive means for said chains is connected to one pair of saidsprockets; and

a guide bar for the upper reach of each of said chains is mounted onsaid inner ladder section, said guide bars being constructed andarranged to engage said rollers of said chains and to receive the weightof said outer ladder section on said chains.

9. A power ladder as defined in claim 8, wherein:

said guide bars are attached to the tops of the rungs of said innerladder section; and

the lower reach of each of said chains is disposed beneath said rungs.

10. In a power ladder as defined in claim 4, wherein:

said workmans operating support is a hollow basket formed of insulatingmaterial;

said position maintaining line means includes line means at each side ofsaid inner and outer sections;

said sides of said outer ladder section and the portion of each saidposition maintaining line means adjacent said support are each formed ofinsulating material;

each side of said inner ladder section is provided with a hollow handrail forming a guide for a corresponding portion of said positionmaintaining line means;

each said position maintaining line means includes a cable extendingaround a sheave mounted on said supporting means;

said extending and retracting line means includes a pair of endlessroller chains connected to the inner end of the underside of therespective sides of said outer ladder section and rotatable sprocketsfor said chains mounted adjacent the outer and inner ends of said innerladder section;

a drive means for said chains is connected to the inner pair of saidsprockets;

a guide bar for the upper reach of each of said chains is mounted on topof the rungs of said inner ladder section, said guide bars beingconstructed and arranged to engage said rollers of said chains and toreceive the weight of said outer ladder section on said chains;

said cable of each of said positioning line means is connected to thelower reach of the corresponding chain, beneath said rungs of said innerladder section; and

a motion opposing shock absorber is pivotally connected between theouter end of each side of said outer ladder section and the rear of saidbasket.

References Cited UNITED STATES PATENTS 2,928,493 3/1960 Clements 18222,936,848 5/1960 Hall 182-2 2,938,594 5/1960 Eitel 182-2 3,078,9492/1963 Hoard et al. 1822 3,243,123 3/1966 'Ingraham et al. 18223,301,346 1/1967 Verrell et a1 1822 REINALDO P. MACHADO, PrimaryExaminer.

